What Is TADS:

The Western Interconnection relies on a network of about 136,000 circuit-miles of transmission to carry electricity from generating plants to load centers. Unplanned outages increase flow on transmission elements in service, potentially causing them to overload or trip. The loss of transmission elements can also cause the loss of generation and lead to reduced system stability.

Availability information for transmission elements is collected through the NERC Transmission Availability Data System (TADS).

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In this section of the report, the information is not shown by region or BA. This section shows how the Western Interconnection is doing overall, so the map and regional functions are not present. However, in this section, the use of statistical significance is introduced.

The chart on the right shows the historical data that is selected by the filters and a trend line over the last five years. The summary box shows the change per year, a p-value (a statistical measure showing the significance of the trend), and a flag that shows whether something is significant.